Brief Description Of The Prior Art
Many types of thread protector devices have previously been constructed and utilized for the purpose of preventing damage to external threads carried at the end of a section of casing, as that casing section is hoisted in a well derrick preparatory to coupling the casing to a section being extended into the well. Generally these thread protectors have been cup-shaped in overall general configuration, so that the threaded end of the casing section can be extended into a cavity or recess in the cup. The remainder of the cup will then surround the threads and prevent them from being struck by metallic structures on the derrick or by other sections of casing.
Two types of such elastomeric thread protectors which have previously been patented are those which are shown in Janzen U.S. Pat. No. 4,398,566 and Janzen U.S. Pat. No. 4,415,005.